Neutron calibration facility with radioactive neutron sources at KRISS

Park, Hyeonseo; Kim, Jungho; Choi, Kil-Oung

doi:10.1093/rpd/ncm034

Cited by 16 publications

(6 citation statements)

References 2 publications

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“…The dimension of the neutron irradiation room is 6.6×7.6×6.3 m 3 . The source was installed ~ 1.5 m underground and positioned at the center of the room on the remote system [3]. The distance between the source and the phantom surface was 50 cm.…”

Section: Methodsmentioning

confidence: 99%

Dose dependence and uncertainty evaluation of calibration factors for active neutron personal dosimeters

Kim

Park

Choi

et al. 2014

Progress in Nuclear Science and Technology

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Active neutron personal dosimeters are now widely used to monitor the neutron personal dose equivalent. They are calibrated periodically in the standard neutron fields such as 252 Cf, D 2 O-moderated 252 Cf, and 241 Am-Be sources. Type B uncertainty of calibration factors should be determined if they are not offered by the manufacturer. DMC 2000 GN and EPD-N2 dosimeters were chosen to evaluate Type B uncertainties. Dose dependence of calibration factors and minimum dose to the dose indication were also investigated with 252 Cf source neutrons in the neutron irradiation room at Korea Research Institute of Standards and Science. The neutron dose was irradiated up to around 10 mSv for studying dose dependence. The calibration factor of EPD-N2 was stable above neutron dose around 2 mSv and that of DMC 2000 GN was stable above around 1 mSv. Type B uncertainties of DMC 2000 GN and EPD-N2 were evaluated to be 6 % and 12 % from the serial measurements. Type B uncertainty of EPD-N2 was also evaluated by fitting the normalized normal distribution of calibration factors with Gaussian function from 153 dosimeters. The result was in good agreement with the result from the serial measurement. Study of minimum dose to the dose indication showed that DMC 2000 GN is more sensitive than EPD-N2.

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Section: Methodsmentioning

confidence: 99%

Dose dependence and uncertainty evaluation of calibration factors for active neutron personal dosimeters

Kim

Park

Choi

et al. 2014

Progress in Nuclear Science and Technology

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“…The spectrometer composed of 10 polyethylene spheres from 7.62 cm (3") to 30.48 cm (12") with a 3 He-filled spherical proportional counter (type SP9, Centronic Ltd., UK). Their response functions were calibrated and confirmed with a well-specified 252 Cf neutron source 2) . In this paper, the new technique of the response matrix diagonalization was studied and the responses of the newly developed neutron energy monitoring system were evaluated by detailed Monte Carlo calculations.…”

Section: K0"kpvtqfwevkqp 3 "mentioning

confidence: 96%

“…Six distributions of neutron energy were considered for the weighting. They are flat distribution, 252 Cf distribution in KRISS neutron irradiation room, D 2 O-moderated 252 Cf distribution in KRISS neutron irradiation room 2) , nuclear power plant distribution 1, nuclear power plant distribution 2, and cosmic-ray induced neutron distribution at ground level (altitute 142 m, latitute 36.3916, longitude 127.3690). They are abbreviated "Flat", " 252 Cf(KRISS)", "D 2 O(KRISS)", "NPP1", "NPP2", and "Cosmic", respectively.…”

Section: Progress In Nuclear Science and Technologymentioning

confidence: 98%

Development of a Neutron Energy Monitoring System

Kim

Park

2012

Progress in Nuclear Science and Technology

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The neutron energy measurement is important to evaluate the neutron ambient dose-equivalent. A Bonner sphere spectrometer is a very powerful tool for the measurement of the large dynamic range of neutron energy. However, online monitoring of the neutron energy with Bonner spheres is hard to achieve because of the complex unfolding procedure. For this purpose, the neutron energy monitoring system consisted of a few 3 He proportional counters with cylindrical moderators were developed and their responses were evaluated using MCNPX transport calculations. The range of neutron energy from thermal to 5 GeV was divided into four intervals and six neutron energy spectra were studied to get the weighted average of the response. Spectral neutron fluences of 252 Cf source and D 2 O-moderated 252Cf source were measured in the neutron irradiation room at the Korea Research Institute of Standards and Science. The measured spectra were compared to those by the Bonner sphere spectrometer. The result showed that the neutron energy spectra using the weighted average response of cosmic-ray induced neutron distribution agreed with that obtained by offline analysis of the Bonner sphere spectrometer within 20 %. The system will be used to monitor the environmental neutrons in the near future. KEYWORDS: neutron energy monitoring, response matrix, diagonalization, weighted response K0"Kpvtqfwevkqp 3 "The measurement of the spectral fluence of neutrons is important for evaluating the neutron ambient dose equivalent and widely used to determine a neutron dose. Because of the large dynamic range of neutron energy from meV to a few GeV, there is no practical way to measure the full dynamic range with only a single detector. Many detectors and techniques have been developed to measure the neutron energy. Most common methods are based on the techniques with time-of-flight, multi-moderator detectors like Bonner sphere spectrometers, and threshold detectors like activation foil sets. Among them, a Bonner sphere spectrometer is a very powerful tool for the measurement of the large dynamic range of neutron energy. It consists of a thermal neutron detector and several polyethylene moderators called Bonner spheres. It could measure neutron energy up to a few GeV with an inlet metal moderator 1) . Conventional neutron ambient dosimeters differ greatly from the conventional true value in the unknown fields. Therefore, online monitoring of the neutron energy is also getting important to supplement the neutron ambient dosimeter. The Bonner sphere spectrometer could be used to monitor neutron energy. However, online monitoring of the neutron energy with Bonner spheres is hard to achieve because of the complex procedure like unfolding. The number of the spheres is usually less than 20 which is much smaller than the typical neutron energy bin size. Prior information such as an initial guess of neutron spectrum is *Corresponding Author, E-mail:jungho@kriss.re.kr © 2012 Atomic Energy Society of Japan, All Rights Reserved. required to do unfolding procedur...

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“…The radioactivity levels in each sample of boric acid powder, silicone rubber, and Boru were measured using a single high-purity germanium (HPGe) detector at Yangyang Laboratory (Y2L) [21,22]. The shielding efficiency of Boru was tested using a thermal neutron field and neutron detection system managed by Korea Research Institute of Standards and Science (KRISS) [23,24]. The production process, radioactivity measurement, and shielding efficiency tests will be introduced.…”

Section: Jinst 17 P10041mentioning

confidence: 99%

“…The thermal neutron flux was approximately 2327 and 80 counts/cm 2 /s inside and outside the graphite, respectively [23]. The 3 He proportional counter SP9 from Centronic was placed next to the graphite and shielded by a Cd cylinder to prevent scattered neutrons from the laboratory environment [24]. A removable 1-mm-thick Cd lid covered the Cd cylinder's flat side facing the graphite.…”

Section: Shielding Efficiencymentioning

confidence: 99%

Development of thermal neutron shield with low radioactivity

Ha¹,

Kim²,

Kim³

et al. 2022

J. Inst.

Self Cite

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The second phase of the Advanced Mo-based Rare process Experiment (AMoRE-II) searches for a neutrino-less double-beta decay of 100Mo. A background level in the region of interest of 3034 ± 10 keV is required to be lower than 10-4 count/(keV kg year). Neutrons can generate background signals by gamma-ray emitting reactions with AMoRE-II detector materials. Thermal neutron shields will be installed inside and outside the lead shield to reduce the neutron flux in the shielding system. The background radioactivity of the inner thermal neutron shield must be low because AMoRE-II requires a low background level. A thermal neutron shield with a high shielding efficiency and low radioactivity was produced by using boric acid powder and silicone rubber. The shielding efficiency was tested to be {99.2 ± 0.25(stat)-0.53 +0.47(syst)}%, and the radioactivities of 40K, 226Ra, 228Ac, and 228Th were measured to be < 9.2 at 90% C.L., 14.2 ± 1.5, < 1.6 at 90% C.L., and 2.83 ± 0.80 mBq/kg, respectively.

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Neutron calibration facility with radioactive neutron sources at KRISS

Cited by 16 publications

References 2 publications

Dose dependence and uncertainty evaluation of calibration factors for active neutron personal dosimeters

Dose dependence and uncertainty evaluation of calibration factors for active neutron personal dosimeters

Development of a Neutron Energy Monitoring System

Development of thermal neutron shield with low radioactivity

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